| java.lang.Object | |||
| ↳ | org.apache.lucene.search.Query | ||
| ↳ | org.apache.lucene.search.MultiTermQuery | ||
| ↳ | org.apache.lucene.search.NumericRangeQuery<T extends java.lang.Number> | ||
Class Overview
A Query that matches numeric values within a
specified range. To use this, you must first index the
numeric values using NumericField (expert: NumericTokenStream). If your terms are instead textual,
you should use TermRangeQuery. NumericRangeFilter is the filter equivalent of this
query.
You create a new NumericRangeQuery with the static factory methods, eg:
Query q = NumericRangeQuery.newFloatRange("weight", 0.3f, 0.10f, true, true);
matches all documents whose float valued "weight" field
ranges from 0.3 to 0.10, inclusive.
The performance of NumericRangeQuery is much better
than the corresponding TermRangeQuery because the
number of terms that must be searched is usually far
fewer, thanks to trie indexing, described below.
You can optionally specify a precisionStep
when creating this query. This is necessary if you've
changed this configuration from its default (4) during
indexing. Lower values consume more disk space but speed
up searching. Suitable values are between 1 and
8. A good starting point to test is 4,
which is the default value for all Numeric*
classes. See below for
details.
This query defaults to CONSTANT_SCORE_AUTO_REWRITE_DEFAULT for
32 bit (int/float) ranges with precisionStep ≤8 and 64
bit (long/double) ranges with precisionStep ≤6.
Otherwise it uses CONSTANT_SCORE_FILTER_REWRITE as the
number of terms is likely to be high. With precision
steps of ≤4, this query can be run with one of the
BooleanQuery rewrite methods without changing
BooleanQuery's default max clause count.
NOTE: This API is experimental and
might change in incompatible ways in the next release.
How it works
See the publication about panFMP,
where this algorithm was described (referred to as TrieRangeQuery):
Schindler, U, Diepenbroek, M, 2008. Generic XML-based Framework for Metadata Portals. Computers & Geosciences 34 (12), 1947-1955. doi:10.1016/j.cageo.2008.02.023
A quote from this paper: Because Apache Lucene is a full-text
search engine and not a conventional database, it cannot handle numerical ranges
(e.g., field value is inside user defined bounds, even dates are numerical values).
We have developed an extension to Apache Lucene that stores
the numerical values in a special string-encoded format with variable precision
(all numerical values like doubles, longs, floats, and ints are converted to
lexicographic sortable string representations and stored with different precisions
(for a more detailed description of how the values are stored,
see NumericUtils). A range is then divided recursively into multiple intervals for searching:
The center of the range is searched only with the lowest possible precision in the trie,
while the boundaries are matched more exactly. This reduces the number of terms dramatically.
For the variant that stores long values in 8 different precisions (each reduced by 8 bits) that
uses a lowest precision of 1 byte, the index contains only a maximum of 256 distinct values in the
lowest precision. Overall, a range could consist of a theoretical maximum of
7*255*2 + 255 = 3825 distinct terms (when there is a term for every distinct value of an
8-byte-number in the index and the range covers almost all of them; a maximum of 255 distinct values is used
because it would always be possible to reduce the full 256 values to one term with degraded precision).
In practice, we have seen up to 300 terms in most cases (index with 500,000 metadata records
and a uniform value distribution).
Precision Step
You can choose any precisionStep when encoding values.
Lower step values mean more precisions and so more terms in index (and index gets larger).
On the other hand, the maximum number of terms to match reduces, which optimized query speed.
The formula to calculate the maximum term count is:
n = [ (bitsPerValue/precisionStep - 1) * (2^precisionStep - 1 ) * 2 ] + (2^precisionStep - 1 )
(this formula is only correct, when bitsPerValue/precisionStep is an integer;
in other cases, the value must be rounded up and the last summand must contain the modulo of the division as
precision step).
For longs stored using a precision step of 4, n = 15*15*2 + 15 = 465, and for a precision
step of 2, n = 31*3*2 + 3 = 189. But the faster search speed is reduced by more seeking
in the term enum of the index. Because of this, the ideal precisionStep value can only
be found out by testing. Important: You can index with a lower precision step value and test search speed
using a multiple of the original step value.
Good values for precisionStep are depending on usage and data type:
- The default for all data types is 4, which is used, when no
precisionStepis given. - Ideal value in most cases for 64 bit data types (long, double) is 6 or 8.
- Ideal value in most cases for 32 bit data types (int, float) is 4.
- For low cardinality fields larger precision steps are good. If the cardinality is < 100, it is
fair to use
MAX_VALUE(see below). - Steps ≥64 for long/double and ≥32 for int/float produces one token
per value in the index and querying is as slow as a conventional
TermRangeQuery. But it can be used to produce fields, that are solely used for sorting (in this case simply useMAX_VALUEasprecisionStep). UsingNumericFieldsfor sorting is ideal, because building the field cache is much faster than with text-only numbers. These fields have one term per value and therefore also work with term enumeration for building distinct lists (e.g. facets / preselected values to search for). Sorting is also possible with range query optimized fields using one of the aboveprecisionSteps.
Comparisons of the different types of RangeQueries on an index with about 500,000 docs showed
that TermRangeQuery in boolean rewrite mode (with raised BooleanQuery clause count)
took about 30-40 secs to complete, TermRangeQuery in constant score filter rewrite mode took 5 secs
and executing this class took <100ms to complete (on an Opteron64 machine, Java 1.5, 8 bit
precision step). This query type was developed for a geographic portal, where the performance for
e.g. bounding boxes or exact date/time stamps is important.
Summary
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Inherited Fields | |||||||||||
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 From class
org.apache.lucene.search.MultiTermQuery
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| Public Methods | |||||||||||
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Returns the field name for this query
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Returns the upper value of this range query
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Returns the lower value of this range query
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Returns
true if the upper endpoint is inclusive | |||||||||||
Returns
true if the lower endpoint is inclusive | |||||||||||
Factory that creates a
NumericRangeQuery, that queries a double
range using the given precisionStep. | |||||||||||
Factory that creates a
NumericRangeQuery, that queries a double
range using the default precisionStep PRECISION_STEP_DEFAULT (4). | |||||||||||
Factory that creates a
NumericRangeQuery, that queries a float
range using the default precisionStep PRECISION_STEP_DEFAULT (4). | |||||||||||
Factory that creates a
NumericRangeQuery, that queries a int
range using the default precisionStep PRECISION_STEP_DEFAULT (4). | |||||||||||
Factory that creates a
NumericRangeQuery, that queries a long
range using the default precisionStep PRECISION_STEP_DEFAULT (4). | |||||||||||
Prints a query to a string, with
field assumed to be the
default field and omitted. | |||||||||||
| Protected Methods | |||||||||||
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Construct the enumeration to be used, expanding the pattern term.
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[Expand]
Inherited Methods | |||||||||||
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From class
org.apache.lucene.search.MultiTermQuery
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From class
org.apache.lucene.search.Query
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From class
java.lang.Object
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Public Methods
public T getMax ()
Returns the upper value of this range query
public T getMin ()
Returns the lower value of this range query
public final int hashCode ()
public boolean includesMax ()
Returns true if the upper endpoint is inclusive
public boolean includesMin ()
Returns true if the lower endpoint is inclusive
public static NumericRangeQuery<Double> newDoubleRange (String field, int precisionStep, Double min, Double max, boolean minInclusive, boolean maxInclusive)
Factory that creates a NumericRangeQuery, that queries a double
range using the given precisionStep.
You can have half-open ranges (which are in fact </≤ or >/≥ queries)
by setting the min or max value to null. By setting inclusive to false, it will
match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
public static NumericRangeQuery<Double> newDoubleRange (String field, Double min, Double max, boolean minInclusive, boolean maxInclusive)
Factory that creates a NumericRangeQuery, that queries a double
range using the default precisionStep PRECISION_STEP_DEFAULT (4).
You can have half-open ranges (which are in fact </≤ or >/≥ queries)
by setting the min or max value to null. By setting inclusive to false, it will
match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
public static NumericRangeQuery<Float> newFloatRange (String field, int precisionStep, Float min, Float max, boolean minInclusive, boolean maxInclusive)
Factory that creates a NumericRangeQuery, that queries a float
range using the given precisionStep.
You can have half-open ranges (which are in fact </≤ or >/≥ queries)
by setting the min or max value to null. By setting inclusive to false, it will
match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
public static NumericRangeQuery<Float> newFloatRange (String field, Float min, Float max, boolean minInclusive, boolean maxInclusive)
Factory that creates a NumericRangeQuery, that queries a float
range using the default precisionStep PRECISION_STEP_DEFAULT (4).
You can have half-open ranges (which are in fact </≤ or >/≥ queries)
by setting the min or max value to null. By setting inclusive to false, it will
match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
public static NumericRangeQuery<Integer> newIntRange (String field, int precisionStep, Integer min, Integer max, boolean minInclusive, boolean maxInclusive)
Factory that creates a NumericRangeQuery, that queries a int
range using the given precisionStep.
You can have half-open ranges (which are in fact </≤ or >/≥ queries)
by setting the min or max value to null. By setting inclusive to false, it will
match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
public static NumericRangeQuery<Integer> newIntRange (String field, Integer min, Integer max, boolean minInclusive, boolean maxInclusive)
Factory that creates a NumericRangeQuery, that queries a int
range using the default precisionStep PRECISION_STEP_DEFAULT (4).
You can have half-open ranges (which are in fact </≤ or >/≥ queries)
by setting the min or max value to null. By setting inclusive to false, it will
match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
public static NumericRangeQuery<Long> newLongRange (String field, Long min, Long max, boolean minInclusive, boolean maxInclusive)
Factory that creates a NumericRangeQuery, that queries a long
range using the default precisionStep PRECISION_STEP_DEFAULT (4).
You can have half-open ranges (which are in fact </≤ or >/≥ queries)
by setting the min or max value to null. By setting inclusive to false, it will
match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
public static NumericRangeQuery<Long> newLongRange (String field, int precisionStep, Long min, Long max, boolean minInclusive, boolean maxInclusive)
Factory that creates a NumericRangeQuery, that queries a long
range using the given precisionStep.
You can have half-open ranges (which are in fact </≤ or >/≥ queries)
by setting the min or max value to null. By setting inclusive to false, it will
match all documents excluding the bounds, with inclusive on, the boundaries are hits, too.
public String toString (String field)
Prints a query to a string, with field assumed to be the
default field and omitted.
The representation used is one that is supposed to be readable
by QueryParser. However,
there are the following limitations:
- If the query was created by the parser, the printed representation may not be exactly what was parsed. For example, characters that need to be escaped will be represented without the required backslash.
- Some of the more complicated queries (e.g. span queries) don't have a representation that can be parsed by QueryParser.
Protected Methods
protected FilteredTermEnum getEnum (IndexReader reader)
Construct the enumeration to be used, expanding the pattern term.
Throws
| IOException |
|---|